replaced observer in viewmodels to observe only once to fix memleek

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/AdoptionDetailFragment.java

@@ -113,6 +113,7 @@ public class AdoptionDetailFragment extends Fragment {
         binding.spinnerAdoptionCustomer.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
             @Override
             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+                if (isUpdatingUI) return;
                 viewModel.onCustomerSelected(position);
             }
             @Override
@@ -122,6 +123,7 @@ public class AdoptionDetailFragment extends Fragment {
         binding.spinnerAdoptionStore.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
             @Override
             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+                if (isUpdatingUI) return;
                 viewModel.onStoreSelected(position);
             }
             @Override

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/AppointmentDetailFragment.java

@@ -89,6 +89,7 @@ public class AppointmentDetailFragment extends Fragment {
         binding.spinnerCustomer.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
             @Override
             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+                if (isUpdatingUI) return;
                 viewModel.onCustomerSelected(position);
             }
             @Override
@@ -98,6 +99,7 @@ public class AppointmentDetailFragment extends Fragment {
         binding.spinnerStore.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
             @Override
             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+                if (isUpdatingUI) return;
                 viewModel.onStoreSelected(position);
             }
             @Override

android/app/src/main/java/com/example/petstoremobile/viewmodels/AdoptionDetailViewModel.java

@@ -13,6 +13,8 @@ import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.DateTimeUtils;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -71,18 +73,17 @@ public class AdoptionDetailViewModel extends ViewModel {
             state.saveButtonText = isEditing ? "Save" : "Add";
             state.isAdoptionIdVisible = isEditing;
             state.isDeleteVisible = isEditing;
-            state.isFeeEnabled = false; // fee is always read-only
+            state.isFeeEnabled = false;
             if (!isEditing) {
                 state.isCustomerEnabled = true;
                 state.isStoreEnabled = true;
-                state.isPetEnabled = false; // until customer selected
+                state.isPetEnabled = false;
-                state.isEmployeeEnabled = false; // until store selected
+                state.isEmployeeEnabled = false;
                 state.isDateEnabled = true;
                 state.isStatusEnabled = true;
                 state.availableStatuses = new String[]{"Pending"};
                 state.selectedStatus = "Pending";
             } else {
-                // edit: date-based logic applied after load
                 state.isCustomerEnabled = false;
                 state.isStoreEnabled = false;
                 state.isPetEnabled = false;
@@ -95,12 +96,12 @@ public class AdoptionDetailViewModel extends ViewModel {
 
     public void loadInitialFormData(boolean isEditing) {
         // Pets are loaded dynamically based on store selection; no pre-load needed.
-        customerRepository.getCustomerDropdowns().observeForever(r -> {
+        observeOnce(customerRepository.getCustomerDropdowns(), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS && r.data != null) {
                 customerList.setValue(r.data);
             }
         });
-        storeRepository.getStoreDropdowns().observeForever(r -> {
+        observeOnce(storeRepository.getStoreDropdowns(), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS && r.data != null) {
                 storeList.setValue(r.data);
             }
@@ -155,7 +156,7 @@ public class AdoptionDetailViewModel extends ViewModel {
     }
 
     private void loadAvailablePetsByStore(Long storeId) {
-        petRepository.getAvailablePetsByStore(storeId).observeForever(r -> {
+        observeOnce(petRepository.getAvailablePetsByStore(storeId), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS && r.data != null) {
                 List<DropdownDTO> dropdowns = new ArrayList<>();
                 for (com.example.petstoremobile.dtos.PetDTO pet : r.data.getContent()) {
@@ -167,7 +168,7 @@ public class AdoptionDetailViewModel extends ViewModel {
     }
 
     private void loadPetPrice(Long petId) {
-        petRepository.getPetById(petId).observeForever(r -> {
+        observeOnce(petRepository.getPetById(petId), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS && r.data != null) {
                 com.example.petstoremobile.dtos.PetDTO pet = r.data;
                 // In edit mode, add the pet to the list so the spinner can display its name
@@ -185,7 +186,7 @@ public class AdoptionDetailViewModel extends ViewModel {
     }
 
     private void loadEmployeesForStore(Long storeId) {
-        storeRepository.getStoreEmployees(storeId).observeForever(r -> {
+        observeOnce(storeRepository.getStoreEmployees(storeId), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS && r.data != null) {
                 employeeList.setValue(r.data);
             }
@@ -217,6 +218,10 @@ public class AdoptionDetailViewModel extends ViewModel {
                 s.isEmployeeEnabled = true;
                 s.isDateEnabled = true;
                 s.isStatusEnabled = true;
+            } else {
+                // Date cleared: disable everything except the date field so user can pick again
+                setAllEditableFieldsEnabled(s, false);
+                s.isDateEnabled = true;
             }
         });
     }
@@ -240,7 +245,7 @@ public class AdoptionDetailViewModel extends ViewModel {
 
     public LiveData<Resource<AdoptionDTO>> loadAdoption() {
         MutableLiveData<Resource<AdoptionDTO>> result = new MutableLiveData<>();
-        adoptionRepository.getAdoptionById(adoptionId).observeForever(resource -> {
+        observeOnce(adoptionRepository.getAdoptionById(adoptionId), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 AdoptionDTO a = resource.data;
                 String formattedStatus = DateTimeUtils.formatStatusFromBackend(
@@ -321,6 +326,21 @@ public class AdoptionDetailViewModel extends ViewModel {
         void run(T target);
     }
 
+    /**
+     * Observes a LiveData once, removing the observer after the first response.
+     * */
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public static class ViewState {
         public boolean isEditing = false;
         public boolean isAdoptionIdVisible = false;

android/app/src/main/java/com/example/petstoremobile/viewmodels/AdoptionListViewModel.java

@@ -11,6 +11,8 @@ import com.example.petstoremobile.repositories.AdoptionRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -53,7 +55,7 @@ public class AdoptionListViewModel extends ViewModel {
         if ("All Statuses".equals(status)) status = null;
 
         isLoading.setValue(true);
-        adoptionRepository.getAllAdoptions(currentPage, PAGE_SIZE, query, status, storeId, date, employeeId).observeForever(resource -> {
+        observeOnce(adoptionRepository.getAllAdoptions(currentPage, PAGE_SIZE, query, status, storeId, date, employeeId), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     List<AdoptionDTO> currentList = reset ? new ArrayList<>() : new ArrayList<>(adoptions.getValue());
@@ -70,13 +72,25 @@ public class AdoptionListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteAdoptions(List<String> ids) {
         return adoptionRepository.bulkDeleteAdoptions(new BulkDeleteRequest(ids));
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/AnalyticsViewModel.java

@@ -8,6 +8,8 @@ import com.example.petstoremobile.dtos.SaleDTO;
 import com.example.petstoremobile.repositories.SaleRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.math.BigDecimal;
 import java.math.RoundingMode;
 import java.util.ArrayList;
@@ -49,7 +51,7 @@ public class AnalyticsViewModel extends ViewModel {
     public void loadAnalytics() {
         isLoading.setValue(true);
         errorMessage.setValue(null);
-        saleRepository.getAllSales(0, 2000, null, null, null, null, "saleDate,desc").observeForever(resource -> {
+        observeOnce(saleRepository.getAllSales(0, 2000, null, null, null, null, "saleDate,desc"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     cachedSales = resource.data.getContent();
@@ -247,6 +249,18 @@ public class AnalyticsViewModel extends ViewModel {
         return "Daily Revenue (" + s + " – " + e + ")";
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public static class FilterState {
         public String startDate = "";
         public String endDate = "";

android/app/src/main/java/com/example/petstoremobile/viewmodels/AppointmentDetailViewModel.java

@@ -15,6 +15,8 @@ import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.DateTimeUtils;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -71,13 +73,13 @@ public class AppointmentDetailViewModel extends ViewModel {
      * Loads initial dropdown data for customers, stores, and services.
      */
     public void loadInitialFormData() {
-        customerRepository.getCustomerDropdowns().observeForever(r -> {
+        observeOnce(customerRepository.getCustomerDropdowns(), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS) customers.setValue(r.data);
         });
-        storeRepository.getStoreDropdowns().observeForever(r -> {
+        observeOnce(storeRepository.getStoreDropdowns(), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS) stores.setValue(r.data);
         });
-        serviceRepository.getAllServices(0, 200, null, "serviceName").observeForever(r -> {
+        observeOnce(serviceRepository.getAllServices(0, 200, null, "serviceName"), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS && r.data != null) services.setValue(r.data.getContent());
         });
     }
@@ -206,7 +208,7 @@ public class AppointmentDetailViewModel extends ViewModel {
      * Loads the list of pets for a specific customer.
      */
     private void loadPetsForCustomer(Long customerId) {
-        petRepository.getCustomerPets(customerId).observeForever(r -> {
+        observeOnce(petRepository.getCustomerPets(customerId), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS) customerPets.setValue(r.data);
         });
     }
@@ -215,7 +217,7 @@ public class AppointmentDetailViewModel extends ViewModel {
      * Loads the list of employees for a specific store.
      */
     private void loadEmployeesForStore(Long storeId) {
-        storeRepository.getStoreEmployees(storeId).observeForever(r -> {
+        observeOnce(storeRepository.getStoreEmployees(storeId), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS) storeEmployees.setValue(r.data);
         });
     }
@@ -227,7 +229,7 @@ public class AppointmentDetailViewModel extends ViewModel {
      */
     public LiveData<Resource<AppointmentDTO>> loadAppointment() {
         MutableLiveData<Resource<AppointmentDTO>> result = new MutableLiveData<>();
-        repository.getAppointmentById(appointmentId).observeForever(resource -> {
+        observeOnce(repository.getAppointmentById(appointmentId), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 AppointmentDTO a = resource.data;
                 isOriginallyCancel = "CANCELLED".equalsIgnoreCase(a.getAppointmentStatus());
@@ -385,6 +387,19 @@ public class AppointmentDetailViewModel extends ViewModel {
         void run(T t);
     }
 
+    /** Observes a LiveData once, removing the observer after the first non-loading response. */
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     /**
      * A Class to show the states of Appointment Detail Fragment.
      */

android/app/src/main/java/com/example/petstoremobile/viewmodels/AppointmentListViewModel.java

@@ -11,6 +11,8 @@ import com.example.petstoremobile.repositories.AppointmentRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -39,7 +41,7 @@ public class AppointmentListViewModel extends ViewModel {
 
     public void loadAppointments(String query, String status, Long storeId, String date, Long employeeId) {
         isLoading.setValue(true);
-        appointmentRepository.getAllAppointments(0, 500, query, status, storeId, date, employeeId).observeForever(resource -> {
+        observeOnce(appointmentRepository.getAllAppointments(0, 500, query, status, storeId, date, employeeId), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     appointments.setValue(resource.data.getContent());
@@ -52,13 +54,25 @@ public class AppointmentListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteAppointments(List<String> ids) {
         return appointmentRepository.bulkDeleteAppointments(new BulkDeleteRequest(ids));
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/CouponListViewModel.java

@@ -9,6 +9,8 @@ import com.example.petstoremobile.dtos.PageResponse;
 import com.example.petstoremobile.repositories.CouponRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -32,7 +34,7 @@ public class CouponListViewModel extends ViewModel {
 
     public void loadCoupons(int page, int size, Boolean active, String discountType, String sort) {
         isLoading.setValue(true);
-        repository.getAllCoupons(page, size, active, discountType, sort).observeForever(resource -> {
+        observeOnce(repository.getAllCoupons(page, size, active, discountType, sort), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     coupons.setValue(resource.data.getContent());
@@ -44,6 +46,18 @@ public class CouponListViewModel extends ViewModel {
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteCoupons(List<Long> ids) {
         return repository.bulkDeleteCoupons(ids);
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/CustomerListViewModel.java

@@ -8,6 +8,8 @@ import com.example.petstoremobile.dtos.CustomerDTO;
 import com.example.petstoremobile.repositories.CustomerRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -36,7 +38,7 @@ public class CustomerListViewModel extends ViewModel {
 
     public void loadCustomers() {
         isLoading.setValue(true);
-        repository.getAllCustomers(0, 200).observeForever(resource -> {
+        observeOnce(repository.getAllCustomers(0, 200), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     customers.setValue(resource.data.getContent());
@@ -49,6 +51,18 @@ public class CustomerListViewModel extends ViewModel {
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public void filter(String query, String status) {
         this.lastQuery = query;
         this.lastStatus = status;

android/app/src/main/java/com/example/petstoremobile/viewmodels/InventoryListViewModel.java

@@ -11,6 +11,8 @@ import com.example.petstoremobile.repositories.InventoryRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -51,7 +53,7 @@ public class InventoryListViewModel extends ViewModel {
         }
 
         isLoading.setValue(true);
-        inventoryRepository.getAllInventory(query, storeId, currentPage, PAGE_SIZE, "product.prodName").observeForever(resource -> {
+        observeOnce(inventoryRepository.getAllInventory(query, storeId, currentPage, PAGE_SIZE, "product.prodName"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     List<InventoryDTO> currentList = reset ? new ArrayList<>() : new ArrayList<>(inventory.getValue());
@@ -68,13 +70,25 @@ public class InventoryListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteInventory(List<String> ids) {
         return inventoryRepository.bulkDeleteInventory(new BulkDeleteRequest(ids));
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/PetDetailViewModel.java

@@ -11,6 +11,8 @@ import com.example.petstoremobile.repositories.PetRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -45,13 +47,13 @@ public class PetDetailViewModel extends ViewModel {
     }
 
     public void loadInitialFormData() {
-        customerRepository.getCustomerDropdowns().observeForever(resource -> {
+        observeOnce(customerRepository.getCustomerDropdowns(), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 customerList.setValue(resource.data);
             }
         });
 
-        storeRepository.getStoreDropdowns().observeForever(resource -> {
+        observeOnce(storeRepository.getStoreDropdowns(), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 storeList.setValue(resource.data);
             }
@@ -134,7 +136,7 @@ public class PetDetailViewModel extends ViewModel {
 
     public LiveData<Resource<PetDTO>> loadPet() {
         MutableLiveData<Resource<PetDTO>> result = new MutableLiveData<>();
-        petRepository.getPetById(petId).observeForever(resource -> {
+        observeOnce(petRepository.getPetById(petId), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 PetDTO pet = resource.data;
                 selectedCustomerId = pet.getCustomerId();
@@ -227,6 +229,17 @@ public class PetDetailViewModel extends ViewModel {
         void run(T target);
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
 
     public static class ViewState {
         public boolean isEditing = false;

android/app/src/main/java/com/example/petstoremobile/viewmodels/PetListViewModel.java

@@ -12,6 +12,8 @@ import com.example.petstoremobile.repositories.PetRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -43,7 +45,7 @@ public class PetListViewModel extends ViewModel {
         if ("All Species".equals(species)) species = null;
 
         isLoading.setValue(true);
-        petRepository.getAllPets(0, 100, query, status, species, storeId, null, "petName").observeForever(resource -> {
+        observeOnce(petRepository.getAllPets(0, 100, query, status, species, storeId, null, "petName"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     pets.setValue(resource.data.getContent());
@@ -56,13 +58,25 @@ public class PetListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeletePets(List<String> ids) {
         return petRepository.bulkDeletePets(new BulkDeleteRequest(ids));
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/ProductListViewModel.java

@@ -10,6 +10,8 @@ import com.example.petstoremobile.repositories.CategoryRepository;
 import com.example.petstoremobile.repositories.ProductRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -38,7 +40,7 @@ public class ProductListViewModel extends ViewModel {
 
     public void loadProducts(String query, Long categoryId) {
         isLoading.setValue(true);
-        productRepository.getAllProducts(query, categoryId, 0, 100, "prodName").observeForever(resource -> {
+        observeOnce(productRepository.getAllProducts(query, categoryId, 0, 100, "prodName"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     products.setValue(resource.data.getContent());
@@ -51,10 +53,22 @@ public class ProductListViewModel extends ViewModel {
     }
 
     public void loadCategories() {
-        productRepository.getCategoryDropdowns().observeForever(resource -> {
+        observeOnce(productRepository.getCategoryDropdowns(), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 categories.setValue(resource.data);
             }
         });
     }
+
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
 }

android/app/src/main/java/com/example/petstoremobile/viewmodels/ProductSupplierListViewModel.java

@@ -13,6 +13,8 @@ import com.example.petstoremobile.repositories.ProductSupplierRepository;
 import com.example.petstoremobile.repositories.SupplierRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -45,7 +47,7 @@ public class ProductSupplierListViewModel extends ViewModel {
 
     public void loadProductSuppliers(String query, Long productId, Long supplierId) {
         isLoading.setValue(true);
-        psRepository.getAllProductSuppliers(0, 100, query, productId, supplierId, "productName").observeForever(resource -> {
+        observeOnce(psRepository.getAllProductSuppliers(0, 100, query, productId, supplierId, "productName"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     productSuppliers.setValue(resource.data.getContent());
@@ -58,19 +60,31 @@ public class ProductSupplierListViewModel extends ViewModel {
     }
 
     public void loadFilterData() {
-        productRepository.getAllProducts(null, null, 0, 100, "prodName").observeForever(resource -> {
+        observeOnce(productRepository.getAllProducts(null, null, 0, 100, "prodName"), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 products.setValue(resource.data.getContent());
             }
         });
 
-        supplierRepository.getAllSuppliers(0, 100, null, "supCompany").observeForever(resource -> {
+        observeOnce(supplierRepository.getAllSuppliers(0, 100, null, "supCompany"), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 suppliers.setValue(resource.data.getContent());
             }
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteProductSuppliers(List<String> ids) {
         return psRepository.bulkDeleteProductSuppliers(new BulkDeleteRequest(ids));
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/PurchaseOrderListViewModel.java

@@ -10,6 +10,8 @@ import com.example.petstoremobile.repositories.PurchaseOrderRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -38,7 +40,7 @@ public class PurchaseOrderListViewModel extends ViewModel {
 
     public void loadPurchaseOrders(String query, Long storeId) {
         isLoading.setValue(true);
-        purchaseOrderRepository.getAllPurchaseOrders(0, 100, query, storeId, "purchaseOrderId,desc").observeForever(resource -> {
+        observeOnce(purchaseOrderRepository.getAllPurchaseOrders(0, 100, query, storeId, "purchaseOrderId,desc"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     purchaseOrders.setValue(resource.data.getContent());
@@ -51,10 +53,22 @@ public class PurchaseOrderListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
+
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
 }

android/app/src/main/java/com/example/petstoremobile/viewmodels/SaleListViewModel.java

@@ -11,6 +11,8 @@ import com.example.petstoremobile.repositories.SaleRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -51,7 +53,7 @@ public class SaleListViewModel extends ViewModel {
         }
 
         isLoading.setValue(true);
-        saleRepository.getAllSales(currentPage, PAGE_SIZE, query, paymentMethod, storeId, isRefund, "saleDate,desc").observeForever(resource -> {
+        observeOnce(saleRepository.getAllSales(currentPage, PAGE_SIZE, query, paymentMethod, storeId, isRefund, "saleDate,desc"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     List<SaleDTO> currentList = reset ? new ArrayList<>() : new ArrayList<>(sales.getValue());
@@ -68,10 +70,22 @@ public class SaleListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
+
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
 }

android/app/src/main/java/com/example/petstoremobile/viewmodels/ServiceDetailViewModel.java

@@ -8,6 +8,8 @@ import com.example.petstoremobile.dtos.ServiceDTO;
 import com.example.petstoremobile.repositories.ServiceRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import javax.inject.Inject;
 
 import dagger.hilt.android.lifecycle.HiltViewModel;
@@ -55,7 +57,7 @@ public class ServiceDetailViewModel extends ViewModel {
 
     public LiveData<Resource<ServiceDTO>> loadService() {
         MutableLiveData<Resource<ServiceDTO>> result = new MutableLiveData<>();
-        repository.getServiceById(serviceId).observeForever(resource -> {
+        observeOnce(repository.getServiceById(serviceId), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 ServiceDTO service = resource.data;
                 updateViewState(state -> {
@@ -106,6 +108,18 @@ public class ServiceDetailViewModel extends ViewModel {
         void run(T target);
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public static class ViewState {
         public boolean isEditing = false;
         public boolean isDeleteVisible = false;

android/app/src/main/java/com/example/petstoremobile/viewmodels/ServiceListViewModel.java

@@ -10,6 +10,8 @@ import com.example.petstoremobile.dtos.ServiceDTO;
 import com.example.petstoremobile.repositories.ServiceRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -46,7 +48,7 @@ public class ServiceListViewModel extends ViewModel {
         }
 
         isLoading.setValue(true);
-        repository.getAllServices(currentPage, PAGE_SIZE, query, "serviceName").observeForever(resource -> {
+        observeOnce(repository.getAllServices(currentPage, PAGE_SIZE, query, "serviceName"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     List<ServiceDTO> currentList = reset ? new ArrayList<>() : new ArrayList<>(services.getValue());
@@ -62,6 +64,18 @@ public class ServiceListViewModel extends ViewModel {
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteServices(List<String> ids) {
         return repository.bulkDeleteServices(new BulkDeleteRequest(ids));
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/StaffListViewModel.java

@@ -10,6 +10,8 @@ import com.example.petstoremobile.repositories.EmployeeRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -42,7 +44,7 @@ public class StaffListViewModel extends ViewModel {
 
     public void loadStaff() {
         isLoading.setValue(true);
-        repository.getAllEmployees(0, 100).observeForever(resource -> {
+        observeOnce(repository.getAllEmployees(0, 100), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     employees.setValue(resource.data.getContent());
@@ -56,13 +58,25 @@ public class StaffListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public void filter(String query, Long storeId, String status) {
         this.lastQuery = query;
         this.lastStoreId = storeId;

android/app/src/main/java/com/example/petstoremobile/viewmodels/SupplierDetailViewModel.java

@@ -8,6 +8,8 @@ import com.example.petstoremobile.dtos.SupplierDTO;
 import com.example.petstoremobile.repositories.SupplierRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import javax.inject.Inject;
 
 import dagger.hilt.android.lifecycle.HiltViewModel;
@@ -55,7 +57,7 @@ public class SupplierDetailViewModel extends ViewModel {
 
     public LiveData<Resource<SupplierDTO>> loadSupplier() {
         MutableLiveData<Resource<SupplierDTO>> result = new MutableLiveData<>();
-        repository.getSupplierById(supId).observeForever(resource -> {
+        observeOnce(repository.getSupplierById(supId), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 SupplierDTO s = resource.data;
                 updateViewState(state -> {
@@ -99,6 +101,18 @@ public class SupplierDetailViewModel extends ViewModel {
         void run(T target);
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public static class ViewState {
         public boolean isEditing = false;
         public boolean isDeleteVisible = false;

android/app/src/main/java/com/example/petstoremobile/viewmodels/SupplierListViewModel.java

@@ -9,6 +9,8 @@ import com.example.petstoremobile.dtos.SupplierDTO;
 import com.example.petstoremobile.repositories.SupplierRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -33,7 +35,7 @@ public class SupplierListViewModel extends ViewModel {
 
     public void loadSuppliers(String query) {
         isLoading.setValue(true);
-        repository.getAllSuppliers(0, 100, query, "supCompany").observeForever(resource -> {
+        observeOnce(repository.getAllSuppliers(0, 100, query, "supCompany"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     suppliers.setValue(resource.data.getContent());
@@ -45,6 +47,18 @@ public class SupplierListViewModel extends ViewModel {
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteSuppliers(List<String> ids) {
         return repository.bulkDeleteSuppliers(new BulkDeleteRequest(ids));
     }